1. Field of the Invention
The present invention relates to a memory device such as a semiconductor memory card, and more particularly to a memory device capable of effectively utilizing an area with secrecy.
2. Description of the Related Art
In recent years, an IC card that has been extensively used in an electronic business or the like has a memory area in a tamper resistant module. Accordingly, the IC card can securely secretly keep data and has a firm resistance for copy or forgery. However, since the memory area of the IC card has only a small memory capacity as low as several ten-kilo bytes, a large quantity of data cannot be stored.
A technique that an application program (refer it to as an “AP”, hereinafter) stored in the IC card is temporarily saved in a terminal device and the IC card is effectively utilized is disclosed in a Patent Document 1 described below. This IC card generates and manages an encryption key to encode the AP to be saved and then save the encoded AP in the terminal device. To recover the saved AP, the AP received from the terminal device is decoded with the managed encryption key to restore the AP in the memory area of the IC card. For example, the technique is disclosed in a patent reference 1 (JP-A-2000-11101).
However, when the AP stored in the IC card is saved in a terminal device A, if the AP is to be used by a terminal device B except the terminal device A, the terminal device A needs to be connected to the IC card. The saved AP needs to be restored in a memory area in the IC card. After that, the terminal device B needs to be connected to the IC card. Otherwise, the AP saved in the terminal device A needs to be moved to the terminal device B through a network or the like. Then, the terminal device B needs to be connected to the IC card. That is, when the AP is saved outside the IC card, if the AP is used by the terminal device B except the terminal device A in which the AP is saved, an extremely troublesome procedure will be inconveniently required.